Two novice carpenters were working on the same side of a house that was being built. One carpenter noticed that the other was occasionally taking a nail out of his apron, looking at it, and tossing it over his shoulder.
The carpenter asked him. "Why are you throwing away perfectly good nails?"
The other carpenter said, "They're facing the wrong way?"

To that, the carpenter replied. "Well, don't throw them away...they're for the other side of the house!"